4507 Datasheet, PDF (37/115 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4507 Group
(1) Power-on reset
Reset can be performed automatically at power on (power-on re-
set) by connecting a diode and a capacitor to RESET pin. Connect
RESET pin and the external circuit at the shortest distance.
VDD
RESET
pin
(Note 2)
(Note 1)
Pull-up transistor
Internal reset
signal
Watchdog timer
output
WEF
VDD
RESET pin voltage
Reset
state
Internal reset signal
Power-on
Reset released
Notes 1:
This symbol represents a parasitic diode.
2: Applied potential to RESET pin must be VDD or less.
Fig. 35 Structure of reset pin and its peripherals, and power-on reset operation
Table 14 Port state at reset
Name
D0, D1, D4, D5
D2/C, D3/K
P00, P01, P02, P03
P10, P11, P12/CNTR, P13/INT
P20/AIN0, P21/AIN1
P30/AIN2, P31/AIN3
Notes 1: Output latch is set to “1.”
2: Pull-up transistor is turned OFF.
Function
D0, D1, D4, D5
D2, D3
P00–P03
P10–P13
P20, P21
P30, P31
State
High-impedance (Note 1)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
High-impedance (Notes 1, 2)
High-impedance (Note 1)
Rev.3.01 2005.02.04 page 37 of 111
REJ03B0107-0301